Antenna (Toroidal Coil) Description

The antenna is a toroidal coil which creates the electromagnetic field necessary for transponder operation

The antenna is mounted at the ignition lock. It is connected to the antenna driver (electronic PCB integrated in the body of the coil).

This driver is connected to the ISU control unit with a 4 terminal connector.

The antenna is used for transponder operation, based on a sequential function principle:

• Transponder powering (charge) phase, during which the antenna generates an electromagnetic field using a frequency of 134.2 kHz; this field induce energy into the transponder by way of this resonant circuit.
• Write phase: sued to transfer commands, addresses and data to the transponder; the principle is a pulse width modulation of the previous electromagnetic field.
• Read phase: the antenna is used as receiver, which demodulates the transponder response signal which is modulated using Frequency Shift Keying.